Main Relay Control Outline; Main Relay Control Block Diagram; Main Relay Control Operation; Drive-By-Wire Control Outline - Mazda RX-8 2004 Service Highlights

MAIN RELAY CONTROL OUTLINE

• When the ignition switch is turned to the ON position, the main relay turns on.
• When the ignition switch is turned from on to off, the main relay turns on for a few minutes to activate the fully-
closed throttle learning function of the drive-by-wire control, the ignition switch off function of the metering oil
pump control, the after-cleaning function of the electrical fan control, and EVAP system leak detection function
of the EVAP control system.
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MAIN RELAY CONTROL BLOCK DIAGRAM

• The PCM controls the main relay on/off, based on commands from the ignition switch or the controls.
IGNITION SWITCH
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MAIN RELAY CONTROL OPERATION

• When the ignition switch is turned to the ON position, the main relay turns on and power is supplied to sensors
and devices.
• When the ignition switch is turned from on to off, a main relay on command signal is received the main relay
turns on and the following actions take place:
1. Throttle valve control: Fully closed throttle learning function (See 01–40–12 DRIVE-BY-WIRE CONTROL
OPERATION.)
2. Ignition switch off function of the metering oil pump control (See 01–40–32 METERING OIL PUMP
CONTROL OPERATION.)
3. After-cooling function of the electrical fan control (See 01–40–37 ELECTRICAL FAN CONTROL
OPERATION.)
4. EVAP system leak detection function of the EVAP control system (See 01–16–7 EVAPORATIVE
EMISSIONS (EVAP) CONTROL SYSTEM OUTLINE.)
• When the on request signal from the controls stop, the main relay turns off.
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DRIVE-BY-WIRE CONTROL OUTLINE

• The drive-by-wire control calculates the optimum target throttle valve opening angle at all ranges of engine
speeds and controls the throttle valve actuator.
• The drive-by-wire control includes idle speed control, accelerator control, traction control, cruise control, and
vehicle speed limiter.
Control List
Control name
Idle speed control
Accelerator control
Traction control
Cruise control
Vehicle speed limiter (AT)
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01–40–10
CONTROL SYSTEM
PCM
• Controls the throttle valve opening angle during idling so that the idle speed is at the
target idle speed.
• Controls the throttle valve opening angle according to the amount of AP depression.
Has a fully-closed throttle learning function for consistent setting of the optimum
throttle opening angle according to changes due to age deterioration.
• Controls the throttle valve opening angle by torque up/down request signals from
the DSC HU/CM and TCM (AT).
• Sets the vehicle speed by operation of the cruise control switch and controls the
throttle valve opening angle so that it becomes close to the set vehicle speed.
• Controls the throttle valve opening angle to lower the vehicle speed when it exceeds
200 km/h {124.3 mph}.
MAIN RELAY
Control Outline
CHU014000140S07
CHU014000140S08
CHU0140S007
CHU014000140S09
CHU014000140S10